GTIs in SPI data analysis

Current SPI data analyses carried out with the spi_science_analysis script are not making use of any GTIs. In order to eliminate ``bad data'', only entire pointing are excluded from the analysis (see Sect. 6.3.1. In addition, the GTIs required to analyse short bursts such as GRBs can be accounted for automatically by the GRB analysis script. In some cases, you may need to create a GTI anyway, and this can be done following the below procedure.

• Create an empty GTI structure

  dal_create obj_name="usergti.fits" template="GNRL-USER-GTI.tpl"

• fill some keywords (if you prefer GUIs, use fv)

       fparkey value=0.0 fitsfile=usergti.fits\~[1] keyword=TSTART
       fparkey value=10000.0 fitsfile=usergti.fits\~[1] keyword=TSTOP
       fparkey value=GOOD fitsfile=usergti.fits\~[1] keyword=GTI\_TYPE
  

  TSTART and TSTOP define the start and end validity of your selection, not the selection itself. The GTI_TYPE can be 'GOOD' (use the time specified in the user GTI file) or 'BAD' (exclude the time specified in the user GTI file)

• open the fits file with fv

  fv usergti.fits

• click on ``Table''
• click on ``Edit''
• select ``Insert'' and then ``row''
• insert as many rows as you want to have good time intervals
• fill in the row either the UTC or the IJD or the OBT columns corresponding to your good/bad time you want to define
• ``Save'' the fits file.